Relationship of botulinum dosage to duration of side effects and normal voice in adductor spasmodic dysphonia.

OBJECTIVE

Objective evaluation of botulinum toxin A (BTX-A) dosing by determination of the statistical relationship between injection amount and duration of side effects and normal voice in adductor spasmodic dysphonia (SD) patients. From this information, to provide a rational guide to determine the initial and follow-up BTX-A amounts for injection.

STUDY DESIGN AND SETTING

Private laryngology clinic. Statistical analysis was performed on data obtained from 101 patients with SD.

RESULTS

Significant and predictable positive correlations were found between duration of side effects and duration of normal voice after BTX-A injection in patients with SD. Dose of BTX-A injected also appeared to have a significant positive correlation with duration of side effects, but a negative correlation with duration of normal voice. A trend toward more severe side effects was seen with larger doses of BTX-A injections.

CONCLUSIONS AND SIGNIFICANCE

Increased understanding of the response of the human voice over time after BTX-A injection at various doses suggests new ideas to further increase clinical efficacy with the use of lower BTX-A doses.